https://gcc.gnu.org/bugzilla/show_bug.cgi?id=89482
--- Comment #8 from Ciro Santilli <ciro.santilli at gmail dot com> --- Thanks for the reply, David. Do you have the doc patch uploaded anywhere to serve as a starting point? Quick things that we might need to change / clarify: - is the x constraint documented somewhere? Mentioned at `b Use with "w" or "x" constraint to print the register's 8bit B name.` - also document the aarch32 modifiers, e.g. %P from this thread - in https://www.limegreensocks.com/arm/Machine-Constraints.html#Machine-Constraints "ARM family" why do we have both 't' and 'w', since as per this thread s0 and d0 are differentiated with a %P modifier? I don't know GCC internals, but I know enough ARM assembly to experimentally verify those very quickly and guess from the relevant source point if not too convoluted, does not look too bad: - ARM: https://github.com/gcc-mirror/gcc/blob/gcc-8_2_0-release/gcc/config/arm/arm.c#L22466 - aarch64: https://github.com/gcc-mirror/gcc/blob/gcc-8_2_0-release/gcc/config/aarch64/aarch64.c#L6743
